From: Michael Bommarito <michael.bommarito@gmail.com> stable inclusion from stable-v5.10.258 commit a132e199de69e2a45628aa8534df1bf5d44e1b6e category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15706 CVE: CVE-2026-53004 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 0cf004ffb61cd32d140531c3a84afe975f9fc7ea ] sctp_getsockopt_peer_auth_chunks() checks that the caller's optval buffer is large enough for the peer AUTH chunk list with if (len < num_chunks) return -EINVAL; but then writes num_chunks bytes to p->gauth_chunks, which lives at offset offsetof(struct sctp_authchunks, gauth_chunks) == 8 inside optval. The check is missing the sizeof(struct sctp_authchunks) = 8-byte header. When the caller supplies len == num_chunks (for any num_chunks > 0) the test passes but copy_to_user() writes sizeof(struct sctp_authchunks) = 8 bytes past the declared buffer. The sibling function sctp_getsockopt_local_auth_chunks() at the next line already has the correct check: if (len < sizeof(struct sctp_authchunks) + num_chunks) return -EINVAL; Align the peer variant with its sibling. Reproducer confirms on v7.0-13-generic: an unprivileged userspace caller that opens a loopback SCTP association with AUTH enabled, queries num_chunks with a short optval, then issues the real getsockopt with len == num_chunks and sentinel bytes painted past the buffer observes those sentinel bytes overwritten with the peer's AUTH chunk type. The bytes written are under the peer's control but land in the caller's own userspace; this is not a kernel memory corruption, but it is a kernel-side contract violation that can silently corrupt adjacent userspace data. Fixes: 65b07e5d0d09 ("[SCTP]: API updates to suport SCTP-AUTH extensions.") Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com> Acked-by: Xin Long <lucien.xin@gmail.com> Link: https://patch.msgid.link/20260416031903.1447072-1-michael.bommarito@gmail.co... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- net/sctp/socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 279d5e9421d3..e20aa4dbf740 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -6863,7 +6863,7 @@ static int sctp_getsockopt_peer_auth_chunks(struct sock *sk, int len, /* See if the user provided enough room for all the data */ num_chunks = ntohs(ch->param_hdr.length) - sizeof(struct sctp_paramhdr); - if (len < num_chunks) + if (len < sizeof(struct sctp_authchunks) + num_chunks) return -EINVAL; if (copy_to_user(to, ch->chunks, num_chunks)) -- 2.43.0